1. Field of the Invention
The present invention relates to: a piezoelectric actuator comprising a plate-like piezoelectric element, a sheet, and a movable body; and a piezoelectric actuator array in which the piezoelectric actuators are arranged in a lattice pattern.
2. Background Art
One of conventional piezoelectric actuators (hereinafter, referred to as a “first conventional device”) comprises a cylindrical piezoelectric element. An entire surface of an inner wall of the cylindrical piezoelectric element is covered with an electrode. Electrodes separated one above the other are formed on an outer surface of the cylindrical piezoelectric element. The lower electrode is formed around the lower portion of the cylindrical piezoelectric element. The upper electrode is divided in a circumferential direction.
The first conventional device expands/contracts the cylindrical piezoelectric element in a center axis direction of the cylinder (height direction) using the lower electrode and the inner wall electrode, and simultaneously, flexuously deforms the cylindrical piezoelectric element using the upper electrode and the inner wall electrode. The first conventional device is configured so as to move a movable body (table) with the deformation of the cylindrical piezoelectric element (refer to a first embodiment of Japanese Patent Application Laid-Open No. 2004-140946).
However, according to the first conventional device, a height of the cylindrical piezoelectric element is long, because the electrode formed on the outer wall must be divided into two parts one above the other, and the flexion-deformity need to be large. Consequently, it has a problem that a size of the piezoelectric actuator is large.
Another of the conventional piezoelectric actuators (hereinafter, referred to as a “second conventional device”) comprises a plurality of piezoelectric elements. Each of a plurality of the piezoelectric elements is formed by stacking, in the Z-axis direction, a piezoelectric element undergoing a shear deformation in the X-axis direction, a piezoelectric element undergoing a shear deformation in the Y-axis direction, and a piezoelectric element undergoing a shear deformation in the Z-axis direction. The second conventional device is configured so as to move a movable body with the deformation of a plurality of the piezoelectric elements (refer to a second embodiment of Japanese Patent Application Laid-Open No. 2004-140946).
However, according to the second conventional device, a height of the piezoelectric actuator is long, because each of the piezoelectric elements is the element in which the “three of the piezoelectric elements are stacked”. Consequently, it has a problem that a size of the piezoelectric actuator is large.
Still another of the conventional piezoelectric actuators (hereinafter, referred to as a “third conventional device”) comprises a layered (stacked) piezoelectric element having a quadratic prism shape. The third conventional device is configured so as to rotate a movable body (round body) by having the layered piezoelectric element undergo appropriate flexion deformation and shear deformation (refer to a second embodiment of Japanese Patent Application Laid-Open No. 2006-238644).
However, according to the third conventional device, it is necessary to enlarge the flexion deformation and the shear deformation in order to move the movable body rapidly, and thus, it is necessary to enlarge a height of the piezoelectric element. Consequently, it has a problem that a size of the piezoelectric actuator is large.
Yet still another of the conventional piezoelectric actuators (hereinafter, referred to as a “fourth conventional device”) is a device in which a piezoelectric element undergoing a shear deformation in the X-axis direction and a piezoelectric element undergoing a shear deformation in the Y-axis direction are stacked, and is configured so as to move a movable body (swivel mirror) using the deformations of those piezoelectric elements (refer to a second embodiment of Japanese Patent Application Laid-Open No. 2009-4775).
However, according to the fourth conventional device, since a single element is “one in which the piezoelectric element undergoing a shear deformation in the X-axis direction and the piezoelectric element undergoing a shear deformation in the Y-axis direction are stacked”, a height of the cylindrical piezoelectric element may be long. Consequently, it has a problem that a size of the piezoelectric actuator is large.